BSA A65 Thunderbolt
BSA A65 Lightning Background & History
The BSA A65 Thunderbolt was the touring version of the 650cc BSA A65 twin. The BSA A65 was brought into production in 1963 when BSA (along with Triumph) converted their big twins from non-unit construction to unit construction. Lucas Electrics (aka ‘The Price of Darkness’ because the lights didn’t always work) supplied the entire British motorcycle and auto industries in from the 1940s through the 1970s, and they were largely responsible for the reputation British bikes got for being unreliable. In 1962, Lucas informed it’s customers that it was discontinuing production of their line of dynamos and magnetos that had been installed on nearly every British motorcycle made. They were replacing it, starting in 1963, with the modern alternator and coil electrical system. It required manufacturers to completely redesign their engines to accommodate them. BSA and Triumph used this as an excuse to convert over to unit construction. The non-unit bikes, the 500cc BSA A7 and the 650cc A10, had been very popular for years. They were replaced by the unit construction 500cc BSA A50 and 650cc BSA A65.
This 1970 BSA A65 Thunderbolt shows what a late 60s T-Bolt looked like. Bold styling with lots of chrome. The TLS front brake arrived in 1968.
BSA A65 Thunderbolt Designed for Touring
The BSA Thunderbolt wasn’t meant to be the fastest bike, it was designed to be easy to ride at speed, with a minimum of vibration. Instead of two carburetors like the hot rod BSA A65 Lightning, the Thunderbolt made do with one Amal Monobloc carb. This provided better drivability at lower speeds while costing some top end horsepower. Where the Lightning made 52 hp and topped 112 mph, the Thunderbolt with its milder state of tune made 46 hp and topped out at 100 mph. Still respectable and very workable within its defined mission. To save costs, as many parts as possible were sourced from BSA’s vast parts bin. The 8-inch single-leading shoe front brake came off the BSA Gold Star. The camshaft was straight out of the Lightning. In keeping with its mission, the BSA Thunderbolt came with a large fuel tank, 3.5 Imperial gallons (4.2 US gal or 16 L). The bike sold well in the all-important US market.
This 1971 BSA A65 Thunderbolt engine shows the single carb very clearly. Note that the frame is 'dove gray'. All 1971 BSA & Triumph big twins got the new oil-bearing frame, BSA painted theirs this color and Triumph painted their black.
BSA A65 Thunderbolt Upgrades
In 1968, BSA’s entire twin-cylinder product lineup benefitted from several improvements. A longer-stroke kick starter made for easier starting; metal tank emblems replaced the old plastic ones that cracked in the sun; the Amal Monobloc carb, prone to flooding when the bike was leaned over on its kickstand was replaced with a same-size Amal Concentric unit. These were so named because the float horseshoed around the jets, rather than off to one side as on the Monobloc.
1971 BSA A65 Thunderbolt. Note the TLS conical front brake.
The End Draws Near
By the late 1960s, quality control problems plagued all of the remaining British motorcycle manufacturers. Poor workmanship at BSA led to oil leaks (more than normal) and bare metal parts rusting on brand new bikes, because they hadn’t been painted. This hurt the reputation among buyers of the BSA A65 Thunderbolt, and all BSA products. Triumph and Norton were having the same problems. When the Japanese finally got into the heavyweight motorcycle market with bikes like the Honda CB750 and the Kawasaki Mach3, it was game over for BSA and the rest of the British motorcycle industry.
The 1972 BSA A65 Thunderbolt has a black frame, where the 1971 models had dove gray.
1971 Redesign of the BSA A65 Thunderbolt
In 1971, <A href='bsa-motorcycles.html'>BSA</a> barely able to keep the lights on, decided to completely redesign its big twins and those of <A href='triumph-motorcycles.html'>Triumph</a> as well. But, they didn’t modernize the engines, which is the one major thing they needed more than anything else. Instead, they left the engines alone and built an all-new frame, call the Oil-in-Frame, because it carried the engine oil inside its backbone instead of in a separate oil tank. They came with all new running gear and bodywork, and were very handsome machines. Traditionalists didn’t like them though, and preferred the old bikes. Either way, they didn’t sell well enough to save BSA. The built their last motorcycle in 1972. Just before they collapsed, they attempted a merger with the only other British motorcycle maker left, Norton-Villiers. <A href='bsa-motorcycles.html'>BSA</a> folded and <A href='norton-motorcycles.html'>Norton</a> ended up owning <A href='triumph-motorcycles.html'>Triumph</a>, but that’s another story.
BSA A65 Books & Products
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"BSA A50 & A65 Factory Repair Manuals" By BSA, 2 booksThis is the same factory issued manual technicians would use in the dealership repair shops for full repairs & overhauls. |
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Available in all sizes, in 5 colors: Black, Gray, Light Gray, Olive Drab & White. Logos are red. |
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